EC-241 OBJECT-ORIENTED PROGRAMMING (OOP) LECTURE 1 Bushra Riaz

COURSE OUTLINE Course Code: EC-241 Credits: 4 (3,1) Prerequisites: EC-111 Algorithms and Computing Text Book C++ How to Program, Deitel and Deitel, 7th Edition, ISBN-10: 0-13-611726-0, Prentice Hall, 2009 References Object Oriented Programming with C++, Robert Lafore, 4th Edition, ISBN-10: 0-672-32308-7, Sams, 2002 The complete Reference C++, Herber Schildt, 3rd Edition The Unified Modeling Language User Guide, Booch, Rumbaugh, Addison- Wesley, ISBN-10: 0-321-26797-4, 2nd Edition, 2005

COURSE OUTLINE Introduction: Procedural versus Object Oriented Programming (OOP), characteristics of OOP, advantages of OOP, Abstract Data Types (ADT), information hiding, encapsulation. Classes and Objects: Classes, objects, access specifiers, data members, member functions, properties, getters and setters, object aggregation. Constructors and Destructors: Default constructors, overloaded constructors, copy constructor, conversion constructor, shallow vs. deep copy.

COURSE OUTLINE Static Members: Static data members and static member functions. Generic Programming and Overloading: Function overloading, operator overloading, templates, C++ standard template library (STL). Dynamic memory management for objects: Pointers to objects, reference variables

COURSE OUTLINE Inheritance and Polymorphism: Inheritance, types of inheritance, derived classes, function overriding, dynamic binding, polymorphism, virtual functions. Streams and Files: Stream classes, File objects, File operations with streams. Object-Oriented Design: Introduction to Unified Modeling Language (UML).

Evaluation Methods: Assignments Quizzes Midterm exams Final Exam Lab Project

PROCEDURAL VS. OBJECT-ORIENTED LANGUAGES Procedural Language Views a program as a series of steps to be carried out E.g. C, FORTRAN, Pascal Object Oriented Language Views a program as a group of objects that have certain properties and can perform certain functions E.g. C++, Java, C#

PROCEDURAL VS. OBJECT-ORIENTED LANGUAGES Problems with Procedural Languages Cannot cope with very large project sizes Expensive software errors (e.g. air traffic control) Causes of Problems Unrestricted Access to Data Global data is allowed Access to data by multiple functions means many connections between functions Programs become difficult to understand, modify and maintain

PROCEDURAL VS. OBJECT-ORIENTED LANGUAGES Poor Modeling of Real World Things Real world things are integral collections of data and functions e.g. a car: has data (make, model etc.) and functions (acceleration) Procedural languages do not tie up data with functions

Example Procedural program 1. Gather ingredients Flour, butter, egg, sugar etc 2. preheat oven to 350 degree 3. beat eggs and butter 4. add sugar 5. mix 6. bake 10 mins

Example Object Oriented programing Model for an Object Properties List of ingridients, or set of data Methods List of actions or instructions

Example Object Oriented programing Baker { Properties (ingredients) Flour Butter Eggs Milk Cake pan Oven Methods (actions) Bake cookies Bake cake Bake pie } 1. Gather ingredients Flour, butter, egg, sugar etc 2. preheat oven to 350 degree 3. beat eggs and butter 4. add sugar 5. mix 6. bake 10 mins

THE PROCEDURAL PARADIGM Global Data Function

GOAL OF OOP Clearer, more reliable, more easily maintained programs More effective way of coping with program complexity

OBJECT-ORIENTED LANGUAGES Most widely used Largest programmer base Java Lacks certain features, e.g. multiple inheritance, pointers, templates Less powerful than C++ (but more safe, of course) C# Emerging

THE OO APPROACH The fundamental idea is to combine into a single unit both data and functions that operate on the data. Such a unit is called an “Object”. An object’s functions are called “member functions” in C++ And its data is called “ data members”.

THE OO APPROACH An object’s data is typically accessed through its member functions, i.e. it is hidden from accidental alteration Data and its function are said to be encapsulated into a single entity Data encapsulation and data hiding are key elements of object-oriented languages

THE OO APPROACH If you want to modify data in an object, you know exactly what functions interact with it (i.e. the member functions of the object). This simplifies writing, debugging, and maintaining the programs An OO program consists of a number of objects which communicate with each other’s member functions

THE OBJECT-ORIENTED PARADIGM Data Member Function object

CHARACTERISTICS OF OO LANGUAGES Objects Classes Encapsulation Inheritance Polymorphism and overloading

CLASSES Objects belong to classes A class and an object of that class has the same relationship as a data type and a variable All objects with the same characteristics (data and functions) constitute one class. A class serves only as a plan, or a template, or sketch- of a number of similar things It merely specifies what data and what functions will be included in objects of that class.

CLASSES Declaring a class doesn’t create any objects, just as mere existence of data type int doesn’t create any variables. A class is thus a description of a no. of similar objects. For instance, HUMAN is a class, and JOHN is its instance (object)

Encapsulation Information hiding Encapsulation is the mechanism that binds together code and the data it manipulates, and keep both safe from outside inteference and missuse Data Member Function object

INHERITANCE Derive other (sub-)classes from an existing class The original class is called the BASE CLASS; the others are DERIVED CLASSES Each class shares common characteristics with the class from which it was derived, and can also add its own modifications, additions. For instance, VEHICLE is a class from which CAR, TRUCK, BUS, MOTORCYCLE classes can be derived.

INHERITANCE Base class F Feature A Feature B Feature D Feature F Feature C Feature D Feature E Feature F Derived classes

POLYMORPHISM AND OVERLOADING Using operators or functions in different ways depending on what they are operating on is called polymorphism (lit. one thing with several distinct forms) Overloading is a special case of polymorphism, e.g. +, -, /, << etc.

C AND C++ C++ C

EXAMPLE PROGRAM IN C++ #include <iostream> using namespace std; int main() { cout<<“Every age has a language of its own\n”; return 0; }

PROGRAM EXPLANATION <iostream> using namespace std int main() This header supports C++ I/O operations. iostream is to C++ what stdio.h is to C using namespace std This tells the compiler to use the std name space std::cout This is the namespace in which the entire Standard C++ library is declared This is required when we use the names that are brought into the program by the processor directive #include<iostream> int main()

PROGRAM EXPLANATION cout Stream The Operator << An object Predefined in C++ to correspond with the “standard output stream” Stream An abstraction that refers to a flow of data The standard output stream normally flows to the screen The Operator << Directs the contents of the variable on its right to the object on its left.

INPUT WITH cin int main() { int ftemp; cout<<“Enter temperature in fahrenheit: “; cin>>ftemp; int ctemp=(ftemp-32)*5/9; cout<<“Equivalent in celsius is : “<<ctemp; cout<<endl; return 0; }